Corvids Part 1: HoodedxCarrion Crow Hybrids

Finally I had time to post this first part in a preliminary study of the Corvids of Dresden.
I haven't had much time for birding lately due to work, moving, and less than comfortable weather; can't wait to go home to Cape May next week for a 2 week holiday, during which I will have much field time!

In this first part, I would like to talk about my initial observations and impressions of Hooded Crow (Corvus cornix) and Carrion Crow (Corvus corone), as well as the different hybrids visible in the vicinity of Dresden. In part 2 (to come shortly later), I will discuss Rooks and Jackdaws, and flight ID of all Corvid species in the Dresden area. So let's get started!...

Structurally, these two species are very similar, with equal length (44-51cm) and wingspan (84-100cm) according to the 2nd edition of the brilliant fieldguide by Svensson, Mullarney and Zetterström (SMZ). I have yet to find a difference in either basic structure or behavior. So it is easy to see why for so long these two species were lumped and considered to be only geographical races, due to the well-known hybridization within a narrow contact region, until 2002, when Hooded Crow was given full species status again. Prior to 2002, Hooded Crow was Corvus corone cornix. They were split in 2002 after more thorough study revealed that the hybridization between the two corvids was not as prolific as at first thought, and moreover, the hybrid offspring were noted to be less vigorous.

Hooded Crow is wide spread over Northern and Eastern Europe down to the Middle East, with an additional Western population found in Ireland and the northern edge of Scotland. Some short-distance migrating populations in Finland/Russia migrate further east in winter, and some populations migrate westward in winter, and can be found in the eastern half of UK and the western edge of France.

The Carrion Crow is resident in the rest of UK (besides the northern edge of Scotland and Ireland) and West Europe until East Germany in the west, and southward until the northern half of Spain and some populations reportedly migrate southeast into Northern Italy for the winter. Overall, less migratory than Hooded though, and with a smaller range.

The narrow region of contact between the two species, where hybridization occurs, runs northward from the Italian Alps near Switzerland, up through eastern Germany (yes, Dresden!) and probably western Poland to the Baltic Sea coast.

Now for some pics! I apologize for not having great quality photos, but I guess that makes this study especially nice for "GISS":

Above is a typical Carrion Crow, all black with some lilac iridescence on the back. Note the relatively thick bill (compared, e.g., to young Rooks, which lack white at bill base and sometimes can be mistaken for Carrion Crows). Forehead and crown appear quite rounded.  

Here now is a Hooded Crow, showing one obvious difference with Carrion Crow: most of the plummage is  gray, with wings and tail black along with the head (except lower nape) and bib down to the belly. Bill and head shape, though, more or less identical to Carrion Crow.

Now here is what I would like to call a "Type-A" hybrid. This hybrid appears like a Hooded, but with noticeably reduced gray areas; the lower back and underside up to just below the bib are black, leaving only a narrow strip of gray crossing the belly below the bib. On true Hoodeds the gray covers >50% of body, but on all hybrids there is gray but always <50%.

Here is the same bird, from the front. Maybe here the reduced gray compared with normal Hooded Crows is more apparent.

Here we see that hybrid (left) with a Carrion (right). Interesting to note that at least all of the "Type-A" hybrids I have seen have either been alone or with Carrion crows, but never with Hoodeds...interesting, but more observation is needed before making any conclusions about this.

Here is the best photo I have at the moment of the "Type-B" hybrid (if I may), which is similar to Type-A in color pattern, however the gray area is much darker; just a mere shade lighter than the black on the rest of the body. Interesting to note that the few birds of this kind I have seen have mostly been either alone, with other hybrids of its type, or with Hoodeds; only once do I recall seeing it loosly associated with a Carrion. In future, through more careful and detailed observations, I hope to understand the differences between these 2 types of hybrids. Maybe clues to their origins may become evident, as it seems that not much is reported on different hybrids, that I could find. Or perhaps there are more than these 2 types, in which case it doesn't make sense to call them "types"; perhaps there is a continuous range of hybrid phenotypes, from looking almost identical to Hooded Crow parent, all the way to looking almost identical to the Carrion Crow parent?
Any info or advice from other birders more experienced with these hybrids is very much welcomed!